Method and system for generating design constraints

Abstract

A method and system for generating design constraints for an electronic circuit design is disclosed. The method and system include reading a design description and an existing design constraint file, configuring design constraint integration rules, writing a new design constraint file, evaluating results of the new design constraint file, and replacing existing design constraint file with the new design constraint file.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of U.S. Provisional Application No. 60 / 873,886 filed on Dec. 8, 2006, which is hereby incorporated by reference in its entirety.BACKGROUND[0002]1. Field[0003]The field of the present invention relates to electronic circuit design and, in particular, to generating design constraints for electronic circuit designs.[0004]2. Description of Related Art[0005]Typically, a design flow at various levels of design abstraction involves specifying design constraints while different synthesis tools optimize the design around these constraints. In case of timing constraints, after synthesis, a static timing analysis is used to verify whether a design is meeting the timing budget. If this is not the case, the static timing analysis produces a critical path report. Typically, static timing analysis ignores the logic function of the gates in the design. Therefore, certain critical paths may turn out to be not sensitizab...

AI Technical Summary

Benefits of technology

The invention is about a method for automatically creating timing constraints for electronic circuits. The method uses structural analysis and formal validation techniques to create top-level constraints and select a small set of potential candidates for false path and multi-cycle-path exceptions, which are then validated using formal validation engines. The methodology supports both RTL and gate-level designs and can generate combinational and sequential timing constraints. The generated timing exceptions can be written in a compressed or uncompressed design constraint format. The technical effect of the invention is to automate the tedious and error-prone manual process of constraint creation and ensure positive impact on the quality of the results downstream in the design process.

Problems solved by technology

There are many challenges in this design process.

First, the design constraints are developed manually and therefore are susceptible to errors.

Second, as the complexity of the designs increases, the design may be partitioned into multiple blocks.

As a result, the design constraints also need to be partitioned accordingly.

Maintaining correctness and consistency in the design constraints between block boundaries and between block constraints and the top-level, full-chip constraints become a challenge.

For that matter, integrating block level design constraints for various IP cores developed at the block level by block owners, into top-level, full-chip design constraints for global timing analysis and synthesis, also becomes a challenge.

Moreover, there might be bugs in the design which cause inconsistencies between functional behavior of a design and a design constraint specification given in a format, such as Cadence Common Timing Engine (CTE) Design Constraint Format, Synopsys Design Constraint (SDC) Format, and / or various other design constraint specifications).

Design constraints may include timing constraints, such as clock characterization, delay specifications, and timing exceptions, such as false path and multi-cycle path exceptions.

Furthermore, it generated timing exceptions for the entire design without considering the exception's impact on the quality of the results downstream.

Unfortunately, in some instances, the constraints are developed manually.

With increasing design size and complexity, these design constraints also increase in number and complexity.

Incorrect and / or incomplete constraints may lead to sub-optimal designs, in terms of area, timing and / or power, or even worse, may lead to silicon failures.

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